1. Field of the Invention
The present invention relates to a data communication apparatus such as a portable information terminal device for wireless radio data communication through light or radio wave.
2. Description of the Related Art
Conventionally, some portable information terminal devices (such as a so-called electronic pocket diary, simplified word processor or personal computer) possess a wireless data communication function utilizing light such as infrared and radio wave. For data communications generally, wire communication networks are used, requiring a connector with a specific size for connection with wire communication networks. Since the portable information terminal unit is designed to be of small size and light weight, a relatively large connector is not desirable. By wireless communication using light or wireless wave, data communications may be achieved without sacrificing the portability of the portable information terminal device.
Between plural portable information terminal devices with data communication capability by the conventional wireless communication, mutual data communications are also possible. In data communications using light, only the data to be transmitted is sent from the transmission side, and it is arranged to receive the data directly at the reception side. In data communications using radio wave, by designating the destination of communication, it is arranged to Send the data to the designated destination.
In conventional data communications by light, the data from the transmission side can be received by all reception sides within the light reaching range, so that data communications to aim only at a specific reception side device is impossible. Accordingly, even if the content of confidential data must be kept secret, the data is able to be received by other reception side devices, so that it is impossible to transmit secret data. In data communications using radio wave, data communication is executed by designation of destination. Accordingly, it is easy to transmit secret data only to the designated destination, but flexible designation as designating plural destinations and transmitting them is available.
Prior art communication from a portable electronic device to another specific device using radio wave is disclosed, for example, in the Japanese Laid-open Patent Hei. 3-296329. This prior art relates to a radio individual calling system such as pager. The purpose of communication is, however, to confirm operation of the radio device for calling, but not to communicate data. Besides, for controlling selection of the destination of communication, a control device is needed aside from the radio device for calling.
Moreover, the data process and communications in the portable information terminal device require completely independent operations. Accordingly, if the data for designating the destination is already included in the stored data, it is necessary to newly enter the data in the operation for designating the destination.